The world's big cities will need $375 billion of investment to curb climate change, a large gathering of mayors heard in Mexico on Thursday. Together we will seek that money, said the new president of the C40 network of big cities, Paris Mayor Anne Hidalgo. The mayors were meeting to plot strategy in the face of climate skepticism from US President-elect Donald Trump. They said they planned to make commitments to reduce harmful emissions by promoting cycling in cities and renewable energy, among other measures.